The sDrive30i uses a 2.0-liter turbo four-cylinder with 255 hp and 255 horsepower 295 lb-ft of torque, posting a 0-60 time of 5.2 seconds with the eight-speed automatic and standard launch control. That compares to the M40i, with a 3.0-liter turbocharged inline-six putting out 382 hp and 369 lb-ft. The sixer does the 60-mph sprint in 4.4 seconds. Back to price comparisons, the Z4 M40i starts at $64,695 before destination, which is $1,665 less than the 2016 sDrive35is RWD that had 335 hp.
The sDrive30i comes standard with LED headlights and the Sport Line trim that adds satin aluminum exterior accents and 18-inch V-spoke orbit gray wheels. Both it and the M40 ride on 18-inch rims with 255-width front tires and 275-width rear tires. Inside, the junior droptop comes with BMW's Live Cockpit Professional Instrument panel, multifunction Sport steering wheel and variable steering, M Sport seats, and dynamic cruise control. A Track Package for the sDrive30i bundles the adaptive dampers, electronically controlled limited-slip differential, and M Sport brakes that come standard on the M40i.
For those keeping tabs on the segment, the 300-hp Porsche 718 Boxster starts at $60,050 out-the-door, about $9,500 more than the Z4 sDrive30i. The Audi TT Roadster goes for $49,395, with 228 hp and 258 lb-ft it's much closer in spec than newness. And the Mercedes-Benz SLC 300 — much older and with an uncertain future — with 241 hp and 273 lb-ft starts at $48,950 before destination, making it $750 less than the Z4.